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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <script>
        // 原型对象的应用 扩展内置对象方法
        var x = [];
        var y = [];
        x.push(2);
        console.log(x);
        console.log(x.push == y.push)
         Array.prototype.sum = function () {
             var sum = 0;
             for (var i = 0; i < this.length; i++) {
                 sum += this[i];
             }
             return sum;
         };
        // Array.prototype = {
        //     sum: function() {
        //         var sum = 0;
        //         for (var i = 0; i < this.length; i++) {
        //             sum += this[i];
        //         }
        //         return sum;
        //     }

        // }
         var arr = [1, 2, 3];
         console.log(arr.sum());
         console.log(Array.prototype);
        var arr = [11, 22, 33];
        console.log(arr.max());
       
            var max = this[0];
            for(var i = 0; i < this.length; i++){
                if(max<this[i])max=this[i]
            }
            return max;
    </script>
</body>

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